Location aware and localized communication is becoming increasingly important. E.g., services such as Google Latitude, Facebook places etc, enable users to share their locations, and the services will adapt based upon where the users are located. The services used by the users will run on User Equipments (UEs). A user equipment is a mobile terminal by which a subscriber may access services offered by an operator. The user equipment may be for example communication devices such as mobile telephones, cellular telephones, smart phones, tablet computers, stationary computers or laptops with wireless capability. The user equipments may be portable, pocket-storable, hand-held, computer-comprised or vehicle-mounted mobile devices, enabled to communicate voice and/or data with another entity, such as another user equipment, a server or any other node in a system.
For example, two users, each having a user equipment, may want to be notified when they are in close proximity to one another. This type of services will likely gain importance in the future, e.g., in social media and augmented reality applications. Further, besides the social media applications, a multitude of use cases for the proximal Internet where the user interacts directly with its surroundings can be imagined.
Device-to-device communication (D2D) is a concept describing that devices, typically user equipment's, communicate directly with each other. Direct communication is here interpreted as communication without any intermediate infrastructure. A prerequisite for D2D communication is that the communicating devices are proximate devices which are aware of each other's physical presence. The D2D communication between devices can be efficient in terms of communication resource usage, energy and bandwidth since the communication does not go via any intermediate infrastructure. D2D communication uses dedicated communication resources or any suitable communications resource which is available in a system. One reason for using the D2D communication is to increase the efficiency relating to energy, bit rate, and Quality of Service (QoS) of systems.
In some examples of D2D communication, devices periodically transmit signals carrying an identity. The identity may also be referred to as an expression. An identity may depend on a certain user or owner of the user equipment, a place, an application, etc. For example, the identity may be tied to a certain group of users on a social media application, such as Facebook, and then identifies a particular user to other members of this user group. In other words, each member of the user group which receives the identity will be able to identify that the user transmitting the identity is nearby. This type of identities are typically private, i.e., only interpretable to an intended group of users. Identities may also be public and carried by shops, restaurants, buses, taxis, museums, etc. This type of identities may be understood by anyone. The identities may be transmitted to a specific receiver, or it may be broadcast in the system. As mentioned above, the system refers to a plurality of user equipment's which understands the identities.
The identification of the identities tells listening and authorized users that the transmitter of the identity is nearby. The transmitter of the identity may be for example a device, a building, a service, etc.